By purifying glassware in a high-temperature Carbolite oven, ELGA LabWater has been able to stop using chromic acid for the preparation of samples in the research and development laboratory where new high-purity water systems are designed. Minimal total organic carbon (TOC) levels, which are used as an indicator of overall organic purity, are a key requirement for users of pure water in laboratories. ELGA’s PURELAB Ultra system achieves TOC levels as low as 1 μg/liter.

In order to keep water samples from being contaminated by organic compounds on the glassware, ELGA used to soak it in chromic acid, which is both toxic and corrosive. Now, following the recommendations in Preparation and Testing of Reagent Water in the Clinical Laboratory (CLSI 4th edition, 2006), sample bottles are rinsed in ultra-pure water, then heated to 450°C for two hours in the high-temperature oven. Tests have shown that any organic contamination present after this procedure is not detectable, according to Paul Whitehead, Ph.D., R&D laboratory manager.

The equipment has a maximum temperature of 500°C and a 60-liter capacity stainless-steel chamber. A PID controller is fitted to ensure temperature stability, and fan-assisted air circulation provides temperature uniformity of better than ±5°C, as well as fast heat-up and recovery times. The ovens are available in three sizes (30, 60 and 120 liters), each with a choice of 400, 500, and 600°C maximum temperatures.